After upgrade, users should not receive notifications for events that took place before they watched a page on the old instance

STEPS TO REPRODUCE

1. Unzip a fresh instance of XWiki (e.g. 11.10.10)
2. Login as Admin
3. Create, update and comment a page
4. Create an user (e.g. U1)
5. Login with U1
6. Go to Notifications Preferences and set Pages toggles to ON (which also sets ON all watch toggles)
7. Close the instance
8. Go to the newer instance (e.g. 12.6.2) and copy/cut the

   [...]webapps\xwiki

   folder and replace it (first delete the old one) in the same location on the older version

9. Start XWiki and follow DW
10. On 'Step 5 - Events migration' migrate events from 'All time'
11. Login with the user U1
12. Observe the notifications list

EXPECTED RESULTS

There are no events in user's notifications list, as the Pages toggles were set to ON after the page was created, updated and commented by Admin on the old instance.

ACTUAL RESULTS

The events are displayed nevertheless in user's notifications list although before the upgrade they were not present there (there's even the U1's profile creation event included).

This may lead to user's notification list being cluttered if there are many events on the wiki.